In recent years, the increase in magnetic disk recording density has been remarkable. A high recording density magnetic disk is manufactured through processes of forming a plurality of magnetic layers over the surface of a substrate. Since an underlayer and a protective layer are respectively provided under and over each of the magnetic layers, the magnetic disk is manufactured through a number of film forming processes. Therefore, in the manufacture of the magnetic disk, use is made of a processing device having a structure with a number of processing chambers arranged for carrying out the respective processes.
For example, when manufacturing one magnetic disk, a disk (substrate) is caused to pass through the number of processing chambers in order so as to be subjected to a predetermined process treatment in each of the processing chambers. In each processing chamber, one-time process treatment is given as one cycle and the same process treatment is repeated each time a disk passes therethrough, and, after the treatment, the disk is sent out to the next processing chamber. Then, a magnetic disk having gone through all the processes is sent out from the final processing chamber.
A sputtering device or apparatus is mainly used as the manufacturing apparatus (processing device) for such high recording density magnetic disks. The sputtering apparatus generates glow discharge by introducing a discharge gas into a vacuum and applying the power to electrodes so as to form a thin film of a target metal on the surface of a disk by collision of ions in a plasma generated by the glow discharge.
In each of processing chambers of the sputtering apparatus, there is a case where film formation is performed on one surface of a single disk, a case where film formation is performed on both surfaces of a single disk, a case where film formation is performed on one surface of each of two disks, a case where film formation is performed on both surfaces of each of two disks, or the like. For example, when simultaneously performing film formation on both surfaces of each of two disks in one processing chamber, it is necessary to provide four cathode electrodes for generating discharge and to apply the power to each of the electrodes.
In the meantime, when manufacturing magnetic disks of this type, it is important to store histories of the manufacturing processes. This is because if a defective product is produced due to occurrence of some abnormality in the manufacturing process, it is possible to pursue a cause thereof later and to promptly correct it.
At a conventional magnetic disk manufacturing site, process-treatment condition data (discharge condition, gas pressure, substrate temperature, etc.) are sampled and the sampled raw data are, as they are, displayed in a graph or the like or stored in storage means. Then, if a defective product is produced, the raw data extracted according to an index of a disk or a lot are, for example, displayed in a graph on a display screen in time sequence, thereby enabling an analysis while observing waveforms in the graph.
FIG. 17 is a block diagram exemplarily illustrating the configuration of a conventional magnetic disk manufacturing system (processing system).
This manufacturing system comprises a processing device (sputtering apparatus) 10 for sputtering a disk being a workpiece W, a control unit 20 for controlling the processing device 10, a sampling unit (raw data collecting means) 30 for collecting raw data on processing conditions (power supply output and gas pressure for generating discharge, substrate temperature, etc.) in the sputtering, a data storage unit (data storage means) 40 for storing the collected data in recording means, and a display/output unit (display means) 50 for displaying in a chart or outputting to another output means the collected data or the stored data according to need.
The processing device 10 is provided with a processing chamber 11 for carrying out a necessary process treatment, a processing unit 12 for carrying out the treatment, a sensor 13 for monitoring the processing state, and so on. Raw data output from the processing unit 12 and the sensor 13 are input into the sampling unit 30. The data output from the sensor 13 and the processing unit 12 may be analog data or digital data. In the sampling unit 30, the raw data are properly converted into a form (digital data form) readable by the data storage unit 40 and the display/output unit 50. Thereafter, the converted data are stored or displayed/output.
The actual magnetic disk manufacturing processing is carried out through a plurality of processes in sequence. Therefore, in the processing device 10, a plurality of processing chambers 11 are arranged so that thin films can be formed on the surface of a disk in a predetermined order. In each of the processing chambers 11, the same process treatment is repeated for each cycle. Since, in this case, the processing device 10 is configured to form magnetic disk thin films on the surface of a disk (substrate) by generation of discharge in the processing chambers 11 each maintained in a predetermined gas pressure atmosphere, respective treatments for forming the thin film are carried out in order in each processing chamber 11.
The sampling unit 20 collects raw data on processing conditions in the processing device 10 and, herein, collects raw data on processing conditions in thin film forming treatments for a number of magnetic disks. For example, it collects raw data such as power supply outputs (power, voltage, current) for generating discharge, gas pressures in the processing chambers 11, and disk temperatures at regular sampling intervals.
Incidentally, in such treatments, acquisition (sampling) of raw data is often performed a plurality of times in the treatment of one process (cycle) in each processing chamber 11. This is for examining time-dependent changes of various parameters in one cycle in detail and, particularly, with respect to such a parameter that largely affects the processing results, it is necessary to carefully observe a change in one process and thus the sampling is performed this way.
When the data thus collected are displayed in time sequence, there is obtained, for example, a graph like FIG. 18. In FIG. 18, the axis of abscissas represents time and the axis of coordinates represents measured value such as discharge voltage.
In the case of this example, the respective components correspond to the following specific means.
(Name)(Example of Specific Means)processing device 10sputtering apparatusprocessing regioninside of chamber(processing chamber 11)processing unit 12sputtering cathode,discharge power supply, etc.sensor 13pressure gauge etc.control unit 20PLCsampling unit 30A/D converterdisplay/output unit 50computerdata storage unit 40hard disk drive